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PAINT.

V specification of Letters Iatent. P t t d M 21 1911 Application filed June 24,1910; Serial no. 568,646.

Be it .known that I, MERnIWEATHER J.

WAUGH, a citizen of the'United'States, re-

siding at Lincoln, Lancaster county, Ne- 5 braska have invented certain new and useful; Improvements in Paints, of, which the "following is a specification. 1

This, invention relates to improvements in paints for-use'principally in' humid climates, (see co-pendingapplication, Serial No. 668,101) and has for its essential object to producea controllable paint coat of heterogneous chemical and physical. structure J tofiwithstand the usualtemperature changes fofya humid. climate, the paint having a maximum of elasticity and adhesive power,

' corresponding with that of the expansion* and contractlon of' the painted surface to which it is applied, thus rendering the same climate proof. It is to be understood that reference to a humid climate is made in contradistinction to normal, dry and arid ch- -mates, where the peculiar weather conditions affect paints differently. In humid climates the paint coatis always provided with a'sufiicient amount of moisture to preveht its be'comin either brittle or-hard, and: the difliculty un er these circumstances is to maintain the coat of sufficient" hardness to prevent its becoming fouled by dust or bruised by-wear.

In" the practice ofthis invention -I have found it desirable to employ a coarse piginent of .chemically stablecharacter and crystalline structure to furnish points for ca'pillar "action for giving a coat. of sufficient t icknessJ To fill the spaces between these coarse Cparticles, .pigments' of "great fineness areded, bothfor the purposeof shielding the-easily destroyed linoxyn (drled ".li nsee'd oil) from atmospheric action and'to render this oil coat impermeable by gases andmoistiire, as well asto give a hidlng ower or opacity to-the paint. -I have found ie'des'irable to use approximately subwhite lead as the major pigment, since it is not onlyan exceedingly fine grained material (diameter of particle 1/3500 0 inch), but, in addition, it is of great chem calstabil'ity. For general exterior use it 1s necessary ,to employ a hardening agent in limed white lead or other lead the coat, because the coat made with subpigment alone is physically too soft to wlthstand abrasion, and it is for this purpose that approximately 30% zinc oxid is preferably employed. Zinc oxid, when mixed with linseed oil and the proper amount of drier, sets and dries more slowly than white lead. Nevertheless, this drying continues in the forni of progressive oxidation until the surface becomes very hard. A comparison between zinc oxid and white lead paints shows that progresslve oxidation which takes place vwhen white lead dries produces a chalky mixture, while the reverse is true of zinc oxid, which produces a hard, vitreous sur-' face. Owing, therefore, to the diverse effects of the two pigments, a combination of sublimed white lead and zinc is for practical purposes desirable.

Approximately 7% fibrous magnesium sihcate is employed as an inert pigment, since this material has the added physical advantage of presenting what is known as a tooth, which is especially desirable for repainting, and it is inert as an extender or filler in paint and does not combine with any other pigment or vehicle. Fibrous magnesium silicate preferably in the form of comparatively long hairlike crystals of asbestos is desirable, since it tends toremain ing the entire mix. It has been found that substantially 7 of silicate may be safely added to the mixed paint without detracting from its covering property as well as inin suspension and to retain the admixed pigcreasing its wearing quality. .To the aforesaid pigments is added a fourth material (approximately 3%), which preferably is a matter of selection, the essential being that it shall be crystalline in character, with rather obtuse angles, it having been shown that materials of acute angular fracture, exert too much of a retarding or holding influence on the brush, thus making the labor of application excessive. A blend of fine pigments with pigments of moderately angular crystallinity is the only mix so far found which brushes uniformly, and it is to secure a proper modification of this brush;

ing character that the fourth pigment is added thereto. Among the available materials may be cited: Calcite (calcium carbonate), tale (a tabular magnesium silicate),

china clay or kaolinl (hydrated aluminum silicate), barytes (native barium sulfate),

aragonlte vandbther forms of calcium carbonate, plaster-of-Paris (anhydrous calcium sulfate), dolomite and other mixed carbonates, feldspar and other complex silicates.

An analysis discloses that one or more pigments of coarse grain are employed to give a requisite thickness of coat; that two pigments of extreme and uniform fineness and grain are employed to give opacity and impermeability as Well as elasticity and durability; that an added crystalline material is utilized to modify brushing; that .a

selection of materials is made to avoid destructive reaction by the pigments upon the paint vehicle; and that the-same is a mix of non-poisonous character.

Without specifically limiting myself to the foregoing, I claim:

1. In combination with a suitable paint vehicle, a major pigment composed of ap proximately 60% sublimed White lead, ap-

proximately 30% zine oxid, approximately 7% fibrous magnesium silicate, and a fourth pigment, substantially 3%, crystalline in character and of rather obtuse angular formation for facilitating in the application of the paint.

2. In combination with a suitable paint vehicle, a major pigment composed of approximately 60% sublimed white lead, approximately 30% zinc oxid, approximately 7% fibrous magnesium silicate and approximately 3% of crystallized calcium carbonated ct rather obtuse angular formation for facilitating in application of the paint-.-

MERRIWEATHER J. WAUGH'.

Witnesses:

' 'R. A. .WARREN,

RAY C. HALL. 

